**6. References**

292 Biogas

A 1.95 0.42 1.00\*\* 0.50 0.07 0.30 0.58 0.82

The results showed that there were significant differences between B treatment of biogas residue fibre film and control, no significant differences between A, C treatment and control, significant differences between black film and control. There were extremely significant differences between the plastic film, A, C treatment and control, there were significant differences between plastic film and B treatment, no significant differences between plastic film and the black film. It can be seen, the yield of B treatment increased 47% as compared

1. Biogas residue are mainly composed of the fiber, non-metallic minerals, minerals, their mass percentage are 64%, 35% and 1% respectively; cellulose, hemicellulose, lignin and ash are 44.8%,21.9%,15.6% and 17.7% respectively in the biogas residue fiber. The mass percent of biogas residue cellulose is over 5% more than that of rice straw, wheat straw and corn stalk; the mass percent of the hemicellulose is 5% less than that of rice straw,

2. An optimum factors combination is rosin 0.4%, bauxite 4% and wet tensile strength 1.8%, beating degree 40SR°, grammage 80 g/m2, in this case, for the biogas residue fibre film, dry tensile strength can attain more than 30N , wet tensile strength can attain more

3. The rank of importance of the five factors on the dry tensile strength: grammage, beating degree, wet strength agent, bauxite and rosin; on the wet tensile strength: wet strength agent, bauxite, rosin, grammage and beating degree; on the degradation:

4. Biogas residue fibre film has significant effect against weeds as compared with plastic

5. There was no significant difference of conserving moisture between biogas residue fiber

6. In the period of eggplant growth, the rank of the total accumulated temperature: plastic

7. The eggplant yield of biogas residue fiber mulching whose grammage is 80g/m2 is 47%

8. It is feasible to make biodegradable mulching from the biogas residue, in accordance

than12N, the degradation period can attain 35 days to 60 days.

grammage, wet strength agent, bauxite, rosin and beating degree.

more than bare field, and slightly lower than that of the plastic film.

film, black film, biogas residue fibre film and bare field.

LSD0.05 LSD0.01

Mean difference (kg)

*<sup>i</sup> y <sup>i</sup> <sup>F</sup> y* − *y <sup>i</sup> <sup>E</sup> y* − *y <sup>i</sup> <sup>D</sup> y* − *y <sup>i</sup> <sup>C</sup> y* − *y <sup>i</sup> <sup>B</sup> y* − *y*

B 2.25 0.72\* 0.70\* 0.20 0.37 C 1.88 0.35 1.07\*\* 0.57 D 2.45 0.92\*\* 0.50 E 2.95 1.42\*\* F 1.53

Table 4-12. Multiple comparisons of the eggplant yield among treatments

Notes: The significance of symbols were as same as table4-4.

Treatment

with control.

**5. Conclusions** 

wheat straw and corn stalk.

film and bare field.

mulching and the plastic film.

with the agronomic requirement


**14** 

*Hungary* 

**Digestate: A New Nutrient Source – Review** 

Digestate is the by-product of methane and heat production in a biogas plant, coming from organic wastes. Depending on the biogas technology, the digestate could be a solid or a

Digestate contains a high proportion of mineral nitrogen (N) especially in the form of ammonium which is available for plants. Moreover, it contains other macro- and microelements necessary for plant growth. Therefore the digestate can be a useful source of plant nutrients, it seems to be an effective fertilizer for crop plants. On the other hand, the organic fractions of digestate can contribute to soil organic matter (SOM) turnover, influencing the biological, chemical and physical soil characteristics as a soil amendment.

Besides these favourable effects of digestate, there are new researches to use it as solid fuel

For protection of the environment, the recycling of organic materials has essential role. The anaerobic digestion (AD) is an important method to decrease the quantity of organic wastes by utilization them for energy and heat production. The by-product of this process is the

In an AD process, different organic materials could be used alone or in mixture of animal slurries and stable wastes, offal from slaughterhouse, energy crops, cover crops and other field residues, organic fraction of municipal solid wastes (OFMSW), sewage sludge. The quality of digestate as a fertilizer or amendment depends not only on the ingestates but also on the retention time. The longer retention time results in less organic material content of

Biogas technology is known to destroy pathogens. The thermophilic AD increases the rate of elimination of pathogenic bacteria, therefore the amounts of fecal coliforms and enterococcus fulfilled the requirements of EU for hygienic indicators (Paavola & Rintala, 2008). Mesophilic digestion alone may not be adequate for correct hygienization, it needs a separate treatment (70 oC, 60 min., particle size<12 mm) before or after digestion, especially

the digestate because of the more effective methanogenesis (Szűcs et al., 2006).

in the case of animal by-products (Bendixen, 1999; Sahlström, 2003).

**1. Introduction** 

liquid material.

or in the process of methane production.

**2. Origin of digestate** 

digestate.

*Research Institute of Nyíregyháza, RISF, CAAES, University of Debrecen,* 

Marianna Makádi, Attila Tomócsik and Viktória Orosz

